Jesus died once, why does he need to be sacrificed in the eucharist every sunday?
It isn’t a new or different sacrifice each Sunday, it’s the same one and only that has ever been - only it’s outside of time.
And we need to keep bringing ourselves to that sacrifice on Calvary again and again each week because we forget it so quickly, and what graces we receive from it need to be repeated to have good effects on us.
It is an essential part of authentic worship to offer something back to God as a way of thanking him for his providence. The Eucharist (the body and blood of Christ) is the greatest gift God gives us and so it is only fitting that we should offer it back to him, in a non-destructive and unbloody manner, as a way of thanking him.
As the psalmist says:
12What shall I render to the LORD for all his bounty to me? 13I will lift up the cup of salvation and call on the name of the LORD, (Psalm 116:12-13)
We’re not re-sacrificing Him. We’re re-presenting that same sacrifice which is not stuck in time.
As has already been stated, it’s not a NEW sacrifice (or even a reenactment of calvary’s sacrifice)… It is the SAME exact sacrifice. Just as the death of Jesus was sufficient to destroy the wages of sin for all time, so His sacrifice is eternal as well, and extends into forever.
If you’ll look up jewish tradition in the OT on passover sacrfice you will find that in order for sacrifice to be pleasing to God, one must consume the flesh of the sacrificial lamb. As such, the Eucharist IS the body and blood of Jesus, our Lord and MUST be partaken of by all members of the Christian faith.
It’s not every Sunday, it’s every day of the week. Millions of times. And it’s not a new sacrifice each time (Catholics aren’t stupid enough to think that we could re-sacrifice Christ against His will!). It’s the same sacrifice, offered once for all, made present for all.
Christ’s sacrifice has to exist outside of time as well as in time, because Christ exists outside of time as well as in time. If His sacrifice were only in time (on the cross 2000 years ago) then it would only have been His humanity that took part in the sacrifice, not His divinity. This is impossible. But since Christ’s divinity did also take part in the sacrifice, and since His divinity exists outside of time, then the sacrifice also exists outside of time.
Christ is always our High Priest, and a High Priest must have something to offer (not “must have had something to offer once, 2000 years ago”). What He offers continually is His one sacrifice to the Father.
The ongoing re-presentation of His sacrifice, just as His death on the cross, is made possible through His Incarnation. They cannot be separated. True God and True Man, that is how there was a sacrifice 2000 years ago, and there is that same sacrifice made present throughout time and space.